Rotor blade structure for vertical shaft impact crusher

Abstract: A rotor blade structure for a vertical shaft impact crusher which enables the lifetime of blades to increase and facilitates maintenance. In the early stage of wear, it takes place by collision between a blade body (2) of each blade (1), particularly teeth (4) provided thereon, and raw stone. Accordingly, in this stage, rods (9) buried in the blade body (2) do not collide with raw stone. As the wear progresses, the rods (9) become exposed. After the rods (9) have been exposed, raw stone also collides with the rods (9), which have a higher hardness than that of the blade body (2). That is, the blade (1) does not subject the rods (9) to wear from the beginning of use of it, but allows the rods (9) to be subjected to wear after the blade body (2) has become worn to a certain extent.

Description: The present invention relates to a rotor blade structure for a vertical shaft impact crusher according to the preamble of claim 1. More particularly, the present invention relates to a rotor blade structure for a vertical shaft impact crusher for crushing bulk materials, for example, natural rock, into particles of predetermined diameter. 2. Description of the Background Art Bulk materials, e.g., natural rock, are crushed in accordance with various uses, for example, aggregate for concrete, paving stone, subgrade material, etc. One type of crusher used for such crushing process is known as impact crusher. Impact crushers operate on the basis of the principle that rock is accelerated at high speed so as to collide with an impact surface, thereby crushing the rock. Such impact crushers may be roughly divided into two types according to the mode of crushing: anvil type and dead stock type. In the anvil type impact crusher, a rotor having a plurality of blades on the upper side thereof is rotated at high speed, whereby raw stone cast in the crusher is accelerated by the blades and centrifugally discharged so as to collide with anvils which are disposed in a ring shape around the rotor, thereby crushing the raw stone. The anvil type impact crusher is mainly used for the purpose of crushing raw stone having a relatively large diameter by collision to thereby reduced the size of the raw stone. On the other hand, the dead stock type impact crusher is used to smooth the surfaces of particles of raw stone which has already been crushed into gravel of desired size and to make the particle size uniform. That is, the dead stock type impact crusher is similar to the anvil type impact crusher in that raw stone is accelerated by blades, but different from the latter in that a dead stock is formed from crushed raw stone at the periphery of the rotor, and this dead stock is used as an impact surface for crushing raw stone. The US 3 767 127 A1 discloses a crusher of the above kind having a rotor being rotatable into both directions. The supports have a triangular horizontal cross-section pointing to the center of the rotor, and the supports are shielded on both side surfaces by V-shaped impeller shoe assamblies. If one of the impeller surfaces is worn, the direction of rotation is changed and the other surface of the impeller shoe is used. If a different wear occurs in the upper and lower portion of the impeller shoes, they may be turned over. The GB 2 248 410 A1 discloses a crusher comprising a blade member having an insert therein of wear-resistant material for extending the lifetime of the blade member. In either of the anvil type and dead stock type impact crushers, as the service time of the crusher elapses, the blades are worn out. For this reason, manganese steel or other wear-resistant material is used for the blades. However, even if such a material is used, wear of the blades cannot be avoided, and the blades must be frequently replaced with new ones. Various propositions have heretofore been made to reduce the frequency of replacement of the blades and to thereby facilitate maintenance. For example, Japanese Patent Application Public Disclosure (KOKAI) No. 62-193657 (1987) discloses a vertical shaft impact crusher in which a pair of blades, which define a discharge passage, are provided on the upper side of a rotor in symmetry with respect to the radial direction, and the rotor is rotated forwardly and then backwardly, thereby avoiding non-uniform wear of the blades. With this crusher, the range of collision between raw stone and the blades is enlarged by reversing the direction of rotation of the rotor, so that non-uniform wear can be prevented to a certain extent. Therefore, the frequency of replacement of the blades also decreases. However, it does not mean that the lifetime of each individual blade increases, even if the impact crusher is arranged as described above. A great variety of impact crushers have heretofore been known in which the blades are curved to form a dead stock from crushed rock on the rotor along the side surfaces of the blades so that the blades are protected from wear by the dead stock (for example, see Japanese Utility Model Application Public Disclosure (KOKAI) Nos. 64-56834 (1989) and 01-163539 (1989)). In this case, since no dead stock is formed at the outer peripheral ends of the blades, a carbide tip is provided on the outer peripheral end of each blade with the surface of the carbide tip exposed with a view to avoiding wear of the blade. In this type of impact crusher, in which the blades are protected by the dead stock, the lifetime of the blades increases to a certain extent by virtue of the presence of the carbide tip. However, when a blade has become worn in excess of a predetermined level, the whole blade must be replaced with a new one, which is a waste of the blade material. Although the carbide tip is not readily worn out, raw stone directly collides with the carbide tip from the beginning of use of the crusher because it is exposed at the outer peripheral end of each blade. Accordingly, the lifetime of the blades does not increase so much as is expected. SUMMARY OF THE INVENTION The present invention has been accomplished on the basis of the above-described conventional technical background, and aims at attaining the following objects. It is an object of the present invention to provide a rotor blade structure for a vertical shaft impact crusher, which enables the lifetime of blades to increase and thus permits a reduction in the frequency of replacement of the blades. It is another object of the present invention to provide a rotor blade structure for a vertical shaft impact crusher, which allows blades to wear uniformly and thus permits a reduction in the frequency of replacement of the blades. It is still another object of the present invention to provide a rotor blade structure for a vertical shaft impact crusher, which allows only a worn portion of a blade to be replaced, thereby enabling the blade material to be effectively used. To comply with these objects the invention is characterized by the features of claim 1. The present invention provides a rotor blade structure for a vertical shaft impact crusher having a rotor (20) rotatable at high speed about a vertical axis in a forward and a backward direction, a plurality of supports (23) provided on the upper side of an outer periphery of said rotor (20) at a regular angular spacing, and blade members (53) disposed on each of said supports (23) so as to cover both side surfaces of the supports (23) and being releasable and remountable to the supports (23) in an upside down orientation. The blade members (53) are attached to both sides of mounting members (52), which are in turn attached to said supports (23) so as to cover both side surfaces thereof, said mounting members (52) being easily releasable from the supports (23). The rotor blade structure comprises means (68) for detachably retaining said blade member (53) on said mounting member (52), a rigid member (65) provided in a portion of said blade member (53), which protects said mounting member (52), said rigid member (65) extending substantially parallel to said vertical axis and being made of a material having a higher hardness than the material used for the blade member (53), a part of the blade member (53) being accommodated in accommodating spaces (58) provided in the sides of the mounting member (52). The mounting member (52) may be releasably attached to said support (23) by means of a pin (74) extending through coaxial bores (71,72,73) of said mounting member (52) and said support (23). The means (68) for detachably retaining said blade member (53) accommodated in said accommodating space (58) may be a pin (68) extending through coaxial bores (59,63) in said mounting member (52) and said blade member (53), whereby said blade members (53) are readily replacable with new ones by simply pulling out the pins (68). The rigid member (65) may be buried in said blade member (52). Said rigid member (65) may be provided in said blade member (53) in a state of being exposed. The mounting member (52) may be formed in the shape of a square cylinder as a whole, which has an approximately square bore (54) in the center thereof to be fitted onto the support (23) through the bore (54). In the early stage of wear, it takes place by collision between the blade body and raw stone. Accordingly, in this stage, the rigid member does not collide with raw stone. As the wear progresses, the rigid member becomes exposed. After the rigid member has been exposed, raw stone also collides with the rigid member, which has a higher hardness than that of the blade body. That is, the blade in the present invention does not subject the rigid member to wear from the beginning of use of the blade, but allows the rigid member to be subjected to wear after the blade body has become worn to a certain extent. BRIEF DESCRIPTION OF THE DRAWINGS The above and other objects, features and advantages of the present invention will become more apparent from the following description of the preferred embodiments thereof, taken in conjunction with the accompanying drawings, in which like reference numerals denote like elements, and of which: Fig. 1 is a plan view of a rotor to which blades are attached in a first embodiment of the present invention; Fig. 2 is a sectional view taken along the line C-C in Fig. 1; Fig. 3 is a sectional view taken along the line D-D in Fig. 1; Fig. 4 is a sectional view taken along the line H-H in Fig. 5 , showing a part of a blade in the first embodiment of the present invention; Fig. 5 is a view seen from the arrow E-E in Fig. 4 ; Fig. 6 is a sectional view taken along the line F-F in Fig. 4 ; and Fig. 7 is a sectional view taken along the line G-G in Fig. 4 . DETAILED DESCRIPTION OF THE EMBODIMENTS One embodiment of the present invention will be described below with reference to the accompanying drawings. Fig. 1 is a partly-sectioned plan view of a first embodiment of the present invention. Fig. 2 is a sectional view taken along the line C-C in Fig. 1, and Fig. 3 is a sectional view taken along the line D-D in Fig. 1. A blade 51 in this embodiment is a composite blade which is composed of a mounting member 52 attached to a support 23, and a pair of blade members 53 which are supported by the mounting member 52. The mounting member 52 is formed in the shape of a square cylinder as a whole, which has an approximately square bore 54 in the center thereof. The mounting member 52 is fitted onto the support 23 through the bore 54. The mounting member 52 has a pair of circumferentially extending portions 55 respectively provided at both circumferential ends of the outward part thereof as viewed in the radial direction of the rotor 20. The respective ends of the circumferentially extending portions 55 are provided with projections 56 which project outwardly of the rotor 20. The two side surfaces of the mounting member 52 that extend radially of the rotor 20 are each formed with a pair of upper and lower mounting plates 57 which extend circumferentially in parallel to each other and which are contiguous with the respective circumferentially extending portions 55. Each pair of mounting plates 57 define a space 58 therebetween for accommodating a blade member 53. The mounting plates 57 are each provided with a pin insertion bore 59. Fig. 4 is a sectional view of a blade member 53. The blade member 53 has a base 60 and a pair of plates 61 which extend horizontally in parallel to each other from the upper and lower ends, respectively, of the base 60. The base 60 has a narrow portion 62 in the center thereof. A pin insertion bore 63 and a rod burying bore 64 are respectively provided on both sides of the narrow portion 62. A rod 65, which is made of a super hard alloy, is inserted into the rod burying bore 64 and secured therein with an adhesive or the like. The rod 65 need not always be buried, but may be exposed. In such a case, the peripheral surface of the rod 65 may be exposed either partly or wholly except for the upper and lower end portions thereof which are secured to the base 60. The base 60 has step portions 66 respectively formed on the upper and lower sides of an end portion thereof which is closer to the pin insertion bore 63 than the narrow portion 62 (see Figs. 5 and 6 ). The plates 61 are each formed with a step portion 67 corresponding to the step portion 66 (see Fig. 7). The composite blade 51 is attached to the support 23 in a state where the blade members 53 have previously been attached to the mounting member 52. That is, the blade members 53 have their step portions 66 accommodated in the respective accommodating spaces 58 formed in the mounting member 52, and a pin 68 is inserted into the bores 59 and 63 for each blade member 53, thereby allowing the blade members 53 to be retained on the mounting member 52. In this state, the composite blade 51 is fitted onto the support 23. The device for retaining the blade members 53 is not necessarily limited to the pin 68 but may be a bolt, an eccentric clamp, etc. In addition, a liner 69 is disposed at the inward end of the mounting member 52 as viewed in the radial direction of the rotor 20, and a pin 75 is inserted into bores 70, 71, 72 and 73, which are provided in the liner 69, the mounting member 52 and the support 23 so as to align with each other, thereby allowing the composite blade 51 to be retained on the support 23. In consequence of the mounting of the blades 51 onto the respective supports 23, each circumferential end portion of a discharge passage liner 25 is clamped between the rotor body 21 and the mounting member 52. Operation The rotor 20 is rotated back and forth by the drive of a reversible motor. During the forward rotation of the rotor 20, wear mainly takes place on the lower half of one blade member 53 of the blade 51. Therefore, when the first blade member 53 has become worn in excess of a predetermined level, the direction of rotation of the rotor 1 is reversed, thereby subjecting the other blade member 53 to wear. When the second blade member 53 has become worn in excess of a predetermined level, the pin 74 is pulled out, and the blade 51 is removed from the support 23 and turned upside down and then remounted onto the support 23. In this state, the rotor 20 is rotated forwardly and then backwardly, thereby subjecting the remaining half portions of the first and second blade members 53 to wear in the mentioned order. Thus, each blade member 53 can be subjected to wear uniformly over substantially the entire surface thereof. Since the blade 51 can be removed simply by pulling out the pin 74, the operation of removing and remounting the blade 51 is extremely easy. The blade members 53 themselves can also readily be replaced with new ones simply by pulling out the pins 68. After the portion of the blade member 53 that surrounds the rod 65 has become worn, the rod 65 is exposed and worn. That is, in this embodiment, the edges of the plates 61 form an impact surface for collision with raw stone. Accordingly, the plates 61 are readily worn and arcuately hollowed out toward the support 23. Particles of crushed rock collect in the resulting hollow portion to form a dead stock. After such a dead stock has been formed, raw stone collides with the dead stock and is accelerated and then discharged from the discharge passage 44. Other Embodiments Although in the described embodiment a super hard alloy is employed as a material for the rods, which are rigid members, it should be noted that other material, e.g., a ceramic material, may also be employed as long as it has a sufficiently high hardness. Although in the foregoing embodiment the rods are secured by bonding, it should be noted that the rods may be buried by previously placing them in a mold when the blade 1 or the blade member 53 is produced by casting. Further, although in the foregoing embodiment rods in the shape of a circular cylinder are employed as rigid members, it is also possible to use rigid members in the shape of a prism, a plate, etc. Thus, it is possible according to the present invention to increase the lifetime of the blades and hence reduce the frequency of replacement of them. In addition, the present invention makes it possible to replace only a worn portion of a blade and hence effectively use the blade material. Although the present invention has been described through specific terms, it should be noted here that the described embodiments are not necessarily exclusive and that various changes and modifications may be imparted thereto without departing from the scope of the invention which is limited solely by the appended claims.

Claims: A rotor blade structure for a vertical shaft impact crusher having a rotor (20) rotatable at high speed about a vertical axis in a forward and a backward direction, a plurality of supports (23) provided on the upper side of an outer periphery of said rotor (20) at a regular angular spacing and comprising each two substantially radially extending side surfaces blade members (53) disposed on each of said supports (23) so as to cover both of said side surfaces of the supports (23), and being releasable and remountable to the supports (23) in an upside down orientation, a rigid member (65) provided in a portion of said blade member (53), said rigid member (65) extending substantially parallel to said vertical axis and being made of a material having a higher hardness than the material used for the blade member (53), characterized by mounting members (52) attached to said supports (23) so as to cover both side surfaces thereof, said mounting members (52) being easily releasable from the supports (23), and being provided each with two substantially radially extending side surfaces, the blade members being each attached to one of said side surfaces of said mounting members, means (68) for detachably retaining said blade member (53) on said mounting member (52), a part of the blade member (53) being accommodated in accommodating spaces (58) provided in the sides of the mounting member (52). A rotor blade structure as claimed in claim 1, characterized in that said mounting member (52) is releasably attached to said support (23) by means of a pin (74) extending through coaxial bores (71,72,73) of said mounting member (52) and said support (23). A rotor blade structure as claimed in claim 1 or 2, characterized in that said means (68) for detachably retaining said blade member (53) accommodated in said accommodating space (58) is a pin (68) extending through coaxial bores (59,63) in said mounting member (52) and said blade member (53), whereby said blade members (53) are readily replacable with new ones by simply pulling out the pins (68). A rotor blade structure as claimed in one of claims 1 to 3, characterized in that said rigid member (65) is buried in said blade member (52). A rotor blade structure as claimed in one of claims 1 to 3, characterized in that said rigid member (65) is provided in said blade member (53) in a state of being exposed. A rotor blade structure as claim in one of the preceding claims, characerized in that said mounting member (52) is formed in the shape of a square cylinder as a whole, which has an approximately square bore (54) in the center thereof to be fitted onto the support (23) through the bore (54).

Inventors: WATAJIMA TERUJI, WATAJIMA, TERUJI
Applicants: NAKAYAMA IRON WORKS LTD, NAKAYAMA IRON WORKS, LTD.
Application year: 1994
Main classification: B02C13
IPC codes: B02C13